hardcoresushi/libgocryptfs
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fusefrontend_reverse: use inomap for inode number translation

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Gets rid of static inode number value limitations.

Fixes https://github.com/rfjakob/gocryptfs/issues/457
This commit is contained in:
Jakob Unterwurzacher 2020-05-03 15:22:10 +02:00
parent db93a6c54c
commit 518771e4e2
7 changed files with 77 additions and 62 deletions
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2
internal/fusefrontend_reverse/reverse_longnames.go
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@ -122,5 +122,5 @@ func (rfs *ReverseFS) newNameFile(relPath string) (nodefs.File, fuse.Status) {
}
content := []byte(rfs.nameTransform.EncryptName(pName, dirIV))
parentFile := filepath.Join(pDir, pName)
return rfs.newVirtualFile(content, rfs.args.Cipherdir, parentFile, inoBaseNameFile)
return rfs.newVirtualFile(content, rfs.args.Cipherdir, parentFile, inoTagNameFile)
}

31
internal/fusefrontend_reverse/rfs.go
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@ -15,6 +15,7 @@ import (
"github.com/rfjakob/gocryptfs/internal/contentenc"
"github.com/rfjakob/gocryptfs/internal/cryptocore"
"github.com/rfjakob/gocryptfs/internal/fusefrontend"
"github.com/rfjakob/gocryptfs/internal/inomap"
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/pathiv"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
@ -38,6 +39,9 @@ type ReverseFS struct {
contentEnc *contentenc.ContentEnc
// Tests wheter a path is excluded (hiden) from the user. Used by -exclude.
excluder ignore.IgnoreParser
// inoMap translates inode numbers from different devices to unique inode
// numbers.
inoMap *inomap.InoMap
}
var _ pathfs.FileSystem = &ReverseFS{}
@ -54,6 +58,7 @@ func NewFS(args fusefrontend.Args, c *contentenc.ContentEnc, n nametransform.Nam
args: args,
nameTransform: n,
contentEnc: c,
inoMap: inomap.New(),
}
fs.prepareExcluder(args)
return fs
@ -180,6 +185,7 @@ func (rfs *ReverseFS) GetAttr(relPath string, context *fuse.Context) (*fuse.Attr
if err != nil {
return nil, fuse.ToStatus(err)
}
rfs.inoMap.TranslateStat(&st)
var a fuse.Attr
a.FromStat(&st)
if rfs.args.ForceOwner != nil {
@ -211,26 +217,25 @@ func (rfs *ReverseFS) GetAttr(relPath string, context *fuse.Context) (*fuse.Attr
}
return &a, status
}
// Normal file / directory
dirfd, name, err := rfs.openBackingDir(pPath)
if err != nil {
return nil, fuse.ToStatus(err)
}
// Stat the backing file/dir using Fstatat
var st unix.Stat_t
err = syscallcompat.Fstatat(dirfd, name, &st, unix.AT_SYMLINK_NOFOLLOW)
syscall.Close(dirfd)
if err != nil {
return nil, fuse.ToStatus(err)
}
// Instead of risking an inode number collision, we return an error.
if st.Ino > inoBaseMin {
tlog.Warn.Printf("GetAttr %q: backing file inode number %d crosses reserved space, max=%d. Returning EOVERFLOW.",
relPath, st.Ino, inoBaseMin)
return nil, fuse.ToStatus(syscall.EOVERFLOW)
var st syscall.Stat_t
{
var st2 unix.Stat_t
err = syscallcompat.Fstatat(dirfd, name, &st2, unix.AT_SYMLINK_NOFOLLOW)
syscall.Close(dirfd)
if err != nil {
return nil, fuse.ToStatus(err)
}
st = syscallcompat.Unix2syscall(st2)
}
rfs.inoMap.TranslateStat(&st)
var a fuse.Attr
st2 := syscallcompat.Unix2syscall(st)
a.FromStat(&st2)
a.FromStat(&st)
// Calculate encrypted file size
if a.IsRegular() {
a.Size = rfs.contentEnc.PlainSizeToCipherSize(a.Size)

52
internal/fusefrontend_reverse/virtualfile.go
View File

@ -10,6 +10,7 @@ import (
"github.com/hanwen/go-fuse/fuse"
"github.com/hanwen/go-fuse/fuse/nodefs"
"github.com/rfjakob/gocryptfs/internal/inomap"
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/pathiv"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
@ -20,19 +21,10 @@ const (
// virtualFileMode is the mode to use for virtual files (gocryptfs.diriv and
// *.name). They are always readable, as stated in func Access
virtualFileMode = syscall.S_IFREG | 0444
// inoBaseDirIV is the start of the inode number range that is used
// for virtual gocryptfs.diriv files. inoBaseNameFile is the thing for
// *.name files.
// The value 10^19 is just below 2^60. A power of 10 has been chosen so the
// "ls -li" output (which is base-10) is easy to read.
// 10^19 is the largest power of 10 that is smaller than
// INT64_MAX (=UINT64_MAX/2). This avoids signedness issues.
inoBaseDirIV = uint64(1000000000000000000)
inoBaseNameFile = uint64(2000000000000000000)
// inoBaseMin marks the start of the inode number space that is
// reserved for virtual files. It is the lowest of the inoBaseXXX values
// above.
inoBaseMin = inoBaseDirIV
// We use inomap's `Tag` feature to generate unique inode numbers for
// virtual files. These are the tags we use.
inoTagDirIV = 1
inoTagNameFile = 2
)
func (rfs *ReverseFS) newDirIVFile(cRelPath string) (nodefs.File, fuse.Status) {
@ -42,20 +34,23 @@ func (rfs *ReverseFS) newDirIVFile(cRelPath string) (nodefs.File, fuse.Status) {
return nil, fuse.ToStatus(err)
}
iv := pathiv.Derive(cDir, pathiv.PurposeDirIV)
return rfs.newVirtualFile(iv, rfs.args.Cipherdir, dir, inoBaseDirIV)
return rfs.newVirtualFile(iv, rfs.args.Cipherdir, dir, inoTagDirIV)
}
type virtualFile struct {
// Embed nodefs.defaultFile for a ENOSYS implementation of all methods
nodefs.File
// pointer to parent filesystem
rfs *ReverseFS
// file content
content []byte
// backing directory
cipherdir string
// path to a parent file (relative to cipherdir)
parentFile string
// inode number of a virtual file is inode of parent file plus inoBase
inoBase uint64
// inomap `Tag`.
// Depending on the file type, either `inoTagDirIV` or `inoTagNameFile`.
inoTag uint8
}
// newVirtualFile creates a new in-memory file that does not have a representation
@ -63,16 +58,17 @@ type virtualFile struct {
// from "parentFile" (plaintext path relative to "cipherdir").
// For a "gocryptfs.diriv" file, you would use the parent directory as
// "parentFile".
func (rfs *ReverseFS) newVirtualFile(content []byte, cipherdir string, parentFile string, inoBase uint64) (nodefs.File, fuse.Status) {
if inoBase < inoBaseMin {
log.Panicf("BUG: virtual inode number base %d is below reserved space", inoBase)
func (rfs *ReverseFS) newVirtualFile(content []byte, cipherdir string, parentFile string, inoTag uint8) (nodefs.File, fuse.Status) {
if inoTag == 0 {
log.Panicf("BUG: inoTag for virtual file is zero - this will cause ino collisions!")
}
return &virtualFile{
File: nodefs.NewDefaultFile(),
rfs: rfs,
content: content,
cipherdir: cipherdir,
parentFile: parentFile,
inoBase: inoBase,
inoTag: inoTag,
}, fuse.OK
}
@ -97,22 +93,18 @@ func (f *virtualFile) GetAttr(a *fuse.Attr) fuse.Status {
}
defer syscall.Close(dirfd)
name := filepath.Base(f.parentFile)
var st unix.Stat_t
err = syscallcompat.Fstatat(dirfd, name, &st, unix.AT_SYMLINK_NOFOLLOW)
var st2 unix.Stat_t
err = syscallcompat.Fstatat(dirfd, name, &st2, unix.AT_SYMLINK_NOFOLLOW)
if err != nil {
tlog.Debug.Printf("GetAttr: Fstatat %q: %v\n", f.parentFile, err)
return fuse.ToStatus(err)
}
if st.Ino > inoBaseMin {
tlog.Warn.Printf("virtualFile.GetAttr: parent file inode number %d crosses reserved space, max=%d. Returning EOVERFLOW.",
st.Ino, inoBaseMin)
return fuse.ToStatus(syscall.EOVERFLOW)
}
st.Ino = st.Ino + f.inoBase
st := syscallcompat.Unix2syscall(st2)
q := inomap.NewQIno(uint64(st.Dev), f.inoTag, uint64(st.Ino))
st.Ino = f.rfs.inoMap.Translate(q)
st.Size = int64(len(f.content))
st.Mode = virtualFileMode
st.Nlink = 1
st2 := syscallcompat.Unix2syscall(st)
a.FromStat(&st2)
a.FromStat(&st)
return fuse.OK
}

16
internal/inomap/inomap.go
View File

@ -15,6 +15,7 @@
package inomap
import (
"fmt"
"log"
"sync"
"syscall"
@ -72,23 +73,30 @@ func (m *InoMap) spill(in QIno) (out uint64) {
func (m *InoMap) Translate(in QIno) (out uint64) {
m.Lock()
defer m.Unlock()
defer func() {
fmt.Printf("Translate: %v -> %d\n", in, out)
}()
if in.Ino > maxPassthruIno {
return m.spill(in)
out = m.spill(in)
return out
}
ns, found := m.namespaceMap[in.namespaceData]
// Use existing namespace
if found {
return uint64(ns)<<48 | in.Ino
out = uint64(ns)<<48 | in.Ino
return out
}
// No free namespace slots?
if m.namespaceNext >= maxNamespaceId {
return m.spill(in)
out = m.spill(in)
return out
}
ns = m.namespaceNext
m.namespaceNext++
m.namespaceMap[in.namespaceData] = ns
return uint64(ns)<<48 | in.Ino
out = uint64(ns)<<48 | in.Ino
return out
}
// TranslateStat translates the inode number contained in "st" if neccessary.

2
internal/inomap/inomap_test.go
View File

@ -106,7 +106,7 @@ func TestUniqueness(t *testing.T) {
var q QIno
outMap := make(map[uint64]struct{})
for q.Dev = 0; q.Dev < 10; q.Dev++ {
for q.Flags = 0; q.Flags < 10; q.Flags++ {
for q.Tag = 0; q.Tag < 10; q.Tag++ {
// some go into spill
for q.Ino = maxPassthruIno - 100; q.Ino < maxPassthruIno+100; q.Ino++ {
out := m.Translate(q)

26
internal/inomap/qino.go
View File

@ -7,9 +7,11 @@ import (
type namespaceData struct {
// Stat_t.Dev is uint64 on 32- and 64-bit Linux
Dev uint64
// Flags acts like an extension of the Dev field.
// Tag acts like an extension of the Dev field.
// It is used by reverse mode for virtual files.
Flags uint8
// Normal (forward) mode does not use it and it
// stays always zero there.
Tag uint8
}
// QIno = Qualified Inode number.
@ -21,15 +23,21 @@ type QIno struct {
Ino uint64
}
// QInoFromStat fills a new QIno struct with the passed Stat_t info.
func QInoFromStat(st *syscall.Stat_t) QIno {
// NewQIno returns a filled QIno struct
func NewQIno(dev uint64, tag uint8, ino uint64) QIno {
return QIno{
namespaceData: namespaceData{
// There are some architectures that use 32-bit values here
// (darwin, freebsd-32, maybe others). Add an explicit cast to make
// this function work everywhere.
Dev: uint64(st.Dev),
Dev: dev,
Tag: tag,
},
Ino: uint64(st.Ino),
Ino: ino,
}
}
// QInoFromStat fills a new QIno struct with the passed Stat_t info.
func QInoFromStat(st *syscall.Stat_t) QIno {
// There are some architectures that use 32-bit values here
// (darwin, freebsd-32, maybe others). Add an explicit cast to make
// this function work everywhere.
return NewQIno(uint64(st.Dev), 0, uint64(st.Ino))
}

10
tests/reverse/inomap_test.go
View File

@ -128,8 +128,10 @@ func TestVirtualFileIno(t *testing.T) {
if origInos.parent == cipherInos.diriv {
t.Errorf("diriv ino collision: %d == %d", origInos.parent, cipherInos.diriv)
}
if origInos.parent != cipherInos.diriv-1000000000000000000 {
t.Errorf("diriv ino mismatch: %d != %d", origInos.parent, cipherInos.diriv)
// Lower 48 bits should come from the backing file
const mask = 0xffffffffffff
if origInos.parent&mask != cipherInos.diriv&mask {
t.Errorf("diriv ino mismatch: %#x vs %#x", origInos.parent, cipherInos.diriv)
}
if origInos.child != cipherInos.child {
t.Errorf("child ino mismatch: %d vs %d", origInos.child, cipherInos.child)
@ -137,7 +139,7 @@ func TestVirtualFileIno(t *testing.T) {
if origInos.child == cipherInos.name {
t.Errorf("name ino collision: %d == %d", origInos.child, cipherInos.name)
}
if origInos.child != cipherInos.name-2000000000000000000 {
t.Errorf("name ino mismatch: %d vs %d", origInos.child, cipherInos.name)
if origInos.child&mask != cipherInos.name&mask {
t.Errorf("name ino mismatch: %#x vs %#x", origInos.child, cipherInos.name)
}
}